27. 二叉树的镜像

一道相似的leetcode题：判断是否为对称的树https://leetcode-cn.com/problems/symmetric-tree/comments/

class Solution(object):
    def isSymmetric(self, root):
        """
        :type root: TreeNode
        :rtype: bool
        """
        def check(node1, node2):
            if not node1 and not node2:
                return True
            elif not node1 or not node2:
                return False

            if node1.val != node2.val:
                return False
            return check(node1.left, node2.right) and check(node1.right, node2.left)

        return check(root, root)

# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    # 返回镜像树的根节点
    def Mirror(self, root):
        # write code here
        if not root:
            return 
        if not root.left and not root.right:
            return 
        root.left, root.right = root.right, root.left
        if root.left:self.Mirror(root.left)
        if root.right:self.Mirror(root.right)
        return root